As a fuel cell, a solid oxide fuel cell (hereinafter, also referred to as SOFC) in which a solid electrolyte (solid oxide) is used has been conventionally known.
In the SOFC, used as an electric power generation unit is a power generation cell (fuel battery cell) in which, for example, a fuel electrode to be in contact with fuel gas is provided in one side of a layer of the solid oxide and an oxidant electrode (air electrode) to be in contact with oxidant gas (atmospheric air) is provided in the other side of the layer of the solid oxide. Moreover, in order to obtain a desired voltage, a stack (fuel cell stack), in which a plurality of fuel battery cells are stack-layered by way of an interconnector, has been developed. The aforementioned fuel cell stack is configured such that fuel gas or air to be used for electric power generation is supplied from a traverse direction perpendicular to a stacking direction of the fuel battery cells. The fuel gas or air then flows along a surface of the fuel electrode and the air electrode. Thereafter, the fuel gas or the air that has been used is discharged from the traverse direction.
Moreover, conventionally, in order to introduce the fuel gas or the air into an inside of the fuel battery cell (inner space in contact with the fuel electrode and the air electrode), a gas-introduction hole (or a gas-discharge hole) and gas flowing paths which communicate with such a hole are provided in a metal frame or the interconnector constituting the fuel battery cell (see, Patent Documents 1 to 3).
Among the above conventional techniques, a fuel cell stack of a flat-plate, stacked-type needs to include a gas flowing path (first gas flowing path) penetrating fuel battery cells in a stacking direction of the fuel cell stack to supply air or fuel gas to each of the fuel battery cells, and also a flowing path (second gas flowing path) extending in a plane direction of the fuel battery cell (i.e., perpendicular to the stacking direction) to supply respective gases from the first gas flowing path to flat-plate electrodes (fuel electrode and air electrode) of each of the fuel battery cells. Generally, the second gas flowing path is formed on an interconnector or a metal frame which holds the fuel battery cell.